1. Field of the Invention
The present invention relates to missile control and propulsion systems and more particularly, to a control system for such involving both reaction and aerodynamics control forces.
2. Description of the Prior Art
Conventional missiles include tail panels mounted for motion about axes generally perpendicular to the axis of the body of the missile. Servo motors are associated with each panel to cause rotation of the panel about its axis. The servo motors are activated by central missile control circuitry. During flight of the missile along a path collinear with the axis of the body of the missile, the tail panels are positioned with their chords parallel with the path of flight. In this position aerodynamic forces acting on the tail panels do not tend to change the attitude of the missile. When an attitude change is required, the tail panels are rotated with respect to the axis of the missile body and therefore with respect to the windstream. The aerodynamic forces applied to the missile by the windstream striking the tail panel surfaces includes a component of force perpendicular to the axis of the missile body which provides the moment necessary to turn the missile. The coordinated positioning of the tail panels by the control circuitry can thereby be utilized to control the attitude and path of flight of the missile.
The boost phase of a typical missile is characterized by very low tail panel effectiveness. To ensure a safe launch and compensate for the reduced effectiveness of the control surfaces, missiles are conventionally ballasted at launch to yield an aerodynamically stable air frame. This results in more than necessary aerodynamic stability after booster burnout with correspondingly reduced pay load capacity and roll-yaw coupling problems during early maneuvering.
One known method of improving boost phase control is to complement the aerodynamic control system with a reaction control system in which the thrust of a reaction motor, such as a jet engine, is used to provide the moment necessary to turn the missile. Presently known reaction control systems for missiles require separate reaction motors for all three missile control channels; pitch, yaw and roll. To provide control, the reaction motors must each have its own servo motor positioning system or be of the controlled thrust variety. Both configurations are limited in their practical usefulness because of the expense and/or complexity of each.
Various examples of pertinent prior art of which the applicant is aware may be found in the following U.S. Pat. Nos. 2,086,545 of Fator; 3,064,419 of Ward; 3,114,520 of Finvold; 3,166,273 of Balluff; and 3,258,916 of Lehmann.